The helicopter landed in the western hills above the San Joaquin Valley and out of the dust walked President John F. Kennedy. It was Aug. 18, 1962, and the sun would not let go. In the hollow of the mountain, where California was about to build its newest reservoir, the air felt like a blast furnace. Summer had baked the earth to a tan and shrunken form. The hills turned to hide. Though not a drop of rain had fallen from the sky since spring, no one in the assembled crowd, certainly not the cotton kings, thought of this as drought.